Electronics and computer systems have become an integral and indispensable part of an aircraft system. While the use of modern technology for communication, control and navigation has made flying safer and more efficient, it also makes the aircraft more susceptible to arcing in its wiring. FIG. 1 is a simplified diagram illustrating an exemplary wiring system for an aircraft. Such exemplary electrical wiring system 1 may include major systems such as power 2, lights 3, and communication 4. For power system 2, it may include sub-systems such as battery, generator and alternator 21, and circuit breakers 22. The communication system may include radio 23 and transponder 24 sub-systems. As can be appreciated, all the systems and sub-systems require wiring to connect the on-board components. Massive amount of wiring, however, also create potential hazards. Many aircraft accidents have been attributed to smoke and fires due to electrical arcing in the aircraft wiring, with the attendant loss of life and damage to property. Heat, arcs or electrical ignition are often caused by loose connections, broken or shorted wires in the power distribution system. In aircraft wiring, vibration, moisture, temperature extremes, improper maintenance, and insulation breakdown all contribute to wiring failure. This may lead to arcing and may ignite combustible components in the aircraft.
Electrical arcing may occur as a result of flexing in the airplane during turbulence, take-off or landing. It may also occur as a result of wire shifting or chafing. It may occur in flight, which could potentially cause smoke, fire and explosion.
In addition, our aircraft fleet is aging and has become even more susceptible to potential faults due to arc faults in the aging wire insulation. This problem is quite predictable, since as the wiring ages, the insulation becomes brittle and begins to break down. However, since the wiring is all encompassed in the aircraft harness, it is generally beyond the maintenance crew's reach. Therefore, in the face of aging fleets, it has become desirable to be able to detect arc faults and shut off the circuit that causes the arc.
While numerous conventional approaches to arc fault detection have been presented, such conventional approaches have not been entirely satisfactory for various reasons, such as failure to detect different types of arcs, vulnerability to generate false alarms, delayed detection and reaction, or simply inaccurate detection. Many rely on conventional time-domain signals and analyses, which compromise the time a system takes to do a detection, while others are only capable of detecting arcs of a single frequency band.
Therefore, it has become desirable to have an arc fault detection system that can detect arcing expediently.
It is also desirable to have an arc fault detection system that can achieve high degree of false alarm immunity.
It is further desirable to have an arc fault detection system that can be easily implemented with the aircraft wiring system.